Applicant's U.S. Pat. No. 6,112,890 describes a packaging system for preserving perishable items; the system of this patent was comprised of a barrier bag. This patent, and prior art cited in it, are the most relevant references known to applicant regarding the technology claimed in this patent application. 
In the packaging of perishable foods, a non-oxidizing environment is needed to prevent the spoiling of the food by oxidation of various food constituents. In the applicant's copending patent application U.S. Ser. No. 09/906,280, filed on Jul. 16, 2001, there is disclosed a process for the packaging of perishable foods in a non-oxidizing environment, in which the perishable food is sealed in a package with a small piece of dry ice (solid carbon dioxide). After the package is sealed, the dry ice sublimes, and purges the ambient air containing approximately 20 percent oxygen through a one-way valve in the wall of the packaging. Accordingly, the atmosphere within the packaging is substantially devoid of oxygen, and the perishable food, typically meat, is protected from oxygen-caused degradation. Such packaging renders the product with a prolonged shelf life for retail sale.
However, the atmosphere within the packaging is substantially free of water vapor as well as oxygen when the sublimation of the dry ice is complete. While this is less of a problem for the packaging of meats, it is clearly unsatisfactory for the packaging of other perishable moisture-containing foods, such as breads, cakes, and other baked goods. The very low humidity inside of the packaging results in excessive drying of the baked goods, which renders them unpleasant to consume, and therefore unable to be sold. There is a need in the packaging of perishable moisture-containing foods, for the packaging to contain the food in an environment that is simultaneously non-oxidizing, and of high humidity.
It is therefore an object of this invention to provide a moisture-containing package for preserving perishable moisture-containing foods.
It is a further object of this invention to provide a self-humidifying package for preserving perishable moisture-containing foods. 
It is an additional object of this invention to provide a method for the packaging of moisture-containing foods which provides such foods with a long shelf life.